Liquid spraying guns



April 14, 1964 H. R. J. KNIGHT 3,128,787 LIQUID sPRAYING GuNs Filed June6, 1961 2 Sheets-Sheet 1 nvenlor Hou/ARD n.1 KNiGHT A ilorneys April 14,1964 I-I. R. J. KNIGHT LIQUID SPRAYING GUNS Filed June 6, 1961 2Sheets-Sheet 2 INvIiN-rokl HowARo RICHARD JAMES KNIGHT v BY ATTORNEYS'United States Patent Oice 3,128,787 Patented Apr. 14., 1964 3,128,787LIQUID SPRAYING GUNS Howard Richard .lames Knight, Leamington Spa,England, assignor, by mesne assignments, to Howard Vincent Schweitzer,Cleveland, Ohio Filed June 6, 1961, Ser. No. 115,159 Claims priority,application Great Britain .lune 15, 196) 8 Claims. (Cl. 137-594) Thisinvention relates to guns for spraying liquids and in particular to gunsfor spraying liquids, such as paint, which may be of `differing colours.

When effecting painting with a spray gun it is often required to effectfrequent changes of colour and this entails the provision of alternativesources of paint supply and the connection thereof to the gun, theturning off of atomising air during the changeover, and the operation ofthe gun to cause Ithe paint of new colour to purge the gun ofthepreviously used colour. In many instances, as for example when the gunis being employed for painting automobile bodies moved automatically inquick succession to the painting position, the change-over and purgingmust be effected quickly, possibly in an interval of less than tenseconds, and the change-over must be effec-ted in a manner such as toavoid contamination of the already painted body either by splashes ofthe new paint, or atomised new paint, during purging of the gun or bydried paint particles or dust which may be dislodged while disconnectingone paint -hose from the gun and connecting another to the gun.

Generally it has been possible -for only one paint hose to be connectedto the gun at any one time and this has rendered diicult the effectingof a quick changeover from one colour to ano-ther and also the avoidanceof contamination as just mentioned. Further, when effecting purging ofthe gun it has been necessary to run to waste a relatively considerableamount of paint which is an expensive commodity.

It is a main object of the present invention to provide a spray gunwhich reduces to a minimum the time necessary for effecting achange-over from one colour to another and which reduces the possibilityof contamination during change-over.

It is a further object of the invention to reduce to a minimum thequantity of paint which is run to waste during purging.

According to the invention there is provided in or for a liquid sprayinggun a service unit including a plurality of liquid entry ports, anatomising air entry port, and a control air entry port, a valve memberoperable selectively to effect communication between any one of theliquid entry ports and a liquid inlet port in a gun-body, an atomisingair passage to connect the atomising air entry port with an atomisingair inlet port in the gunbody and a control air passage to connect Ithecontrol air entry port with a control air inlet port in the gun-body.

In order that the invention may be clearly understood one embodimentthereof will now be described, by way of example, with reference to theaccompanying drawings, in which:

FIGURE l is a side elevation of a service unit for a spray gun and,

FIGURE 2 is a section on line II-II, FIGURE l but with the valve memberin the central position thereof, and

FIGURE 3 is an enlarged section taken on line III-III of FIGURE l.

Referring to the drawings, a spray gun, illustrated diagrammatically inbroken lines, comprises a gun-body 1 from which paint is sprayed in thedirection of arrow 2, FIGURE 1. The spray gun and its mode of operationare well known in the art being of lthe kind manufactured by BinlcsManufacturing Company of Chicago, Illinois, or by The De Vilbiss Companyof Toledo, Ohio. The gun comprises a nozzle ywhich is normally closed bya needle valve and is provided with an atomising air inlet portconnectable with a source which continuously supplies air underpressure, with a liquid inlet port connectable with a source whichcontinuously supplies paint under pressure, and with a control air inletport connectable with a source of air under pressure. Control air isadmitted to the control air inlet port only on demand from the paintingmachine. The needle valve normally obturates Ithe flow of atomising airand of paint but when control air is admitted, as called for by thepainting machine, through the control air inlet port the needle valve isWithdrawn by the control air to permit paint and atornising air to flowto the nozzle.

The service unit according to the present invention is arranged to befitted to this known kind of gun and, as will be described below, isprovided with an atomising air entry port to co-operate with theatomising air inlet port of the gun, with liquid entry ports forselective cooperation with the liquid inlet port of the gun, and with acontrol air entry port for co-operation with the control air inlet portof the gun.

The yservice unit 4is adapted to be secured to the gunbody, as by bolts,not shown, and comprises a housing formed by a frame member 4 and acover plate 5 between which there is located a sealing gasket G, FIG-URE 2. The frame member 4 is provided with a plurality, live as shown inFIGURE l, of liquid entry ports 6 each of which receives, as shown inFIGURE 2, a connector by which a paint hose 7, FIGURE 2, for example aplastic hose, can be connected to the service unit. The frame member isalso provided with an atomising air entry port 8, and a control airentry port 9, each of which is provided with a connector, not shown,similar to the connector for the port 6, which can be connectedrespectively with an a-tomising air hose and a control air hose, notshown. The atomising air entry port 8 is connectable with the atomisingair inlet port 11 in the gun-body 1 by an atomising air passage 12formed in the frame member 4, and Athe control air entry port 9 isconnectable with the control air inlet port `13 in the gunbody by acontrol air passage 14.

A valve member 15 in the shape of a T-shaped quadrant is operable`selectively to effect communication between any one of the liquid entryports 6 and the liquid inlet port 16 formed in gun-body 1. The valvemember includes a rockable hollow spindle 17 which is provided with anexterior annular groove 18, FIGURE 2, which is aligned with the liquidoutlet port 16 and has a hole 19 effecting communication between thegroove 18 and the interior 20 of the spindle. The Valve member "15 issecured to the spindle in any suitable manner and a delivery passage 31which extends therethrough is arranged to effect communication betweenthe interior 20 of the spindle and a liquid entry port 6. One ou-ter endof the spindle is closed by a plug 22, FIGURE 2, and O-sectioned sealingrings 23 effect a liquid-tight seal between the spindle, the cover 5,and the frame member 4. A liq-uid-tight seal between the valve member 15and frame member 4 is effected by washers 3, O-sectioned rings `24, andby springs 25 and balls 1.25, FIGURE 2, which press the valve member 15against the washers 3 which surround the liquid entry ports 6. Thewashers 3 are preferably self-lubricating and are made ofpolytetrauoroethylene. With the arrangement of washers 3 and O-sectionedrings 24 as just described it is found that at any given instant two ofthe `washers 3 are firmly engaged with the valve member 1S and that theremaining annexe? washers 3 are pressed against the member 15 by therings 24 which are engaged therewith. The valve member 15 thus floatsbetween the washers 3 and the balls 125 which are aligned with thesealing washers 3.

Indexing means are provided to locate the delivery passage 21 relativeto any one of the liquid entry ports 6 and, as illustrated in thedrawings, comprises a fixed element 26 on the cover 5, which element isprovided, as shown in FIGURE 1, with slots 27 which are aligned one eachwith the ports 6. An indexing finger 2S which is retainable in any oneof the slots 27 by a spring 29, FIGURE 2, is pivoted at 3i) to a nut 31secured to the spindle 17. The finger 28 is thus rockable with thespindle 17 and is supported for rocking movement about pivot 30 in thegeneral direction of the longitudinal axis of the spindle 17.

The control air passage 14 is connected with the atomising air passage12 by an auxiliary air passage 32, FIGURE l, and a cock 33 rotatable inthe air entry port 3 is arranged to obturate the auxiliary passage 32from the atomising air passage 12, as shown in FIG. 3, or to open theauxiliary passage to the atomising air passage.

As illustrated in FIGURE l the gun with the service unit fitted theretois conditioned to receive paint from the extreme left-hand entry port 6.if now a change-over is to be effected to the centre port 6 the indexingfinger 2S is rocked about pivot 39 counterclockwise, as viewed in FIGURE2, thus releasing the finger from the slot 27 aligned with ythe extremelefthand port 6, FIGURE l, and the iingcr 2.8 is then rotated clockwise,as viewed in FIGURE l, until it is aligned with slot 27 which is alignedwith the center port 6, the finger then being released so that spring 29causes it to enter and be retained in the slot 27 aligned with thecenter port 6. The rotation of finger 2S causes the spindle 17 and valvemember 15 also to be rotated clockwise, as viewed in FIGURE l, so thatthe delivery passage 21 is now aligned with the center port 6. It is nownecessary to operate the gun in order to purge it and when this happensthe atomising air is cut-off from port 11 to avoid the finely atomisedpaint of the new colour from spoiling the preceding work and by rotationof cock 33 is diverted through auxiliary passage 32 into port 13 to openthe needle valve of the gun so that paint issues from the gun as a slowmoving, unatomised, stream thus reducing to a minimum the possibility ofthe paint contaminating an already painted body. At this time there isno control air in passage 14. It will be understood that only the gunand the delivery passage 21 have -to be purged of old paint and this canbe quickly eiected with a minimum of paint of the new colour. Because ofthe sealing arrangements described above very little paint collects inthe passage for the valve member 15 but a drain plug 34, FIGURE 1, isprovided to permit draining of the valve passage. When the paint of newcolour is owing freely from the nozzle the cock 33 is again operated -tore-connect the atomising air to port 11 and the control air to port l13and the gun is then conditioned to eiect spraying operations With thepaint of new colour.

It will be also understood that the change-over can be almostinstantaneously effected and that because it is not necessary todisconnect and connect hoses contamination of an already painted body bydried paint particles or dust is reduced to a minimum.

A gun as described herein can, as mentioned above, be used in anautomatic painting machine, in which event it is pivoted at 35, FIGUREl, to the painting apparatus in known manner, or the gun may be ahand-operated gun.

When the gun is used for automatic painting the paint hoses 7, togetherwith the atomising air hose and the control air hose are so disposedrelative one to the other as to avoid chafing as .the gun pivots throughits operating entry port md control air passage,

l angle, thus avoiding the possible precipitation of dirt on the paintedsurfaces.

I claim:

1. A service unit for a spray gun, said unit comprising a housing havinga plurality of liquid entry ports and a liquid outlet passage, a valvemember located in said housing and including a passage selectivelyconnectable between said liquid outlet passage and any one of the liquidentry ports, said housing including an atomizing air entry portcommunicating with an atomizing air passage by which atomizing air ispassed to a gun, a control air entry port communicating with a controlair passage by which control air is delivered to a gun, an auxiliarypassage in said housing connecting the atomizing air and a cock operableto obturate the auxiliary passage from the atomizing air entry port andto connect said port to the atomizing air passage or to open theauxiliary passage to the atomizing air entry port and close theatomizing air passage whereby atomizing air may be diverted to thecontrol air passage.

2. A service yunit according to claim l wherein said Valve memberincludes a rockable hollow spindle provided with an annular groove whichcommunicates with the interior of said spindle and said liquid outletpassage, said annular groove and interior of the spindle forming part ofsaid selectively connectable passage.

3. A service unit according in claim 2 including indexing meansco-operating with the valve member to locate the selectively connectablepassage relative to any one of said liquid entry ports.

4. A service unit according to claim 3 in which the indexing meanscomprises a fixed element on said housing, slots in said fixed elementaligned one with each of the liquid entry ports, an indexing fingerpivotally mounted on said hollow spindle for rocking movement therewithand for rocking movement relative thereto in the general direction ofthe longitudinal axis of the spindle, and a spring cooperating with saidfinger and tending to retain the finger in one of said slots.

5. A service unit for a spray gun comprising a housing having aplurality of liquid entry ports and a liquid outlet passage, a valvemember located in said housing and including a passage selectivelyconnectable between said liquid outlet passage and any one of the liquidentry ports, a sealing washer surrounding each of said liquid entryports and having one face thereof engaging one face of the valve member,an O-section sealing ring engaging the opposite face of the sealingwasher, pressure members engaging the opposite face of the valve member,and springs urging each said ypressure member into engagement with saidopposite face of the valve member, said housing including an atomizingair entry port com municating with an atomizing air passage by whichatomizing air is passed to a gun, and a control air entry portcommunicating with a control air passage through which control air isdelivered to a gun, an auxiliary passage in said housing connecting theatomizing air entry port and control air passage, and a cock operable toobturate the auxiliary passage from the atomizing air entry vport and toconnect said port Ito the atomizing air passage or to open the auxiliarypassage to the atomizing air entry port and close the atomizing airpassage whereby atomizing air may be diverted to the control airpassage.

6. A service unit according to claim 5 in which the valve memberincludes a rockable hollow spindle provided with an annular groove whichcommunicates with the interior of said spindle and said liquid outletpassage, said annular groove and interior of the spindle forming part ofsaid selectively connectable passage.

7. A service unit according to claim 6 including indexing meansco-operating with the valve member to locate the selectively connectablepassage relative to any one of said liquid entry ports.

8. A service unit according to claim 7 in which the 5 indexing meanscomprises a fixed element on said hous- References Cited in the file ofthis patent ing and defining slots aligned one with each of the liquidUNITED STATES PATENTS entry ports, an indexing iinger pivotally mountedon sa1d hollow spindle for rocking movement therewith and for 712,292Geddes OC- 28, 1902 rocking movement relative thereto in the generaldiree- 5 1,185,344 Philibert May 30, 1916 tion of the longitudinal axisof the spindle, and a spring 2,536,199 McDonald Ian. 2, 1951co-operating with said finger and tending to retain the 2,840,109Wadleigh June 24, 1958 finger in one of said slots.

1. A SERVICE UNIT FOR A SPRAY GUN, SAID UNIT COMPRISING A HOUSING HAVINGA PLURALITY OF LIQUID ENTRY PORTS AND A LIQUID OUTLET PASSAGE, A VALVEMEMBER LOCATED IN SAID HOUSING AND INCLUDING A PASSAGE SELECTIVELYCONNECTABLE BETWEEN SAID LIQUID OUTLET PASSAGE AND ANY ONE OF THE LIQUIDENTRY PORTS, SAID HOUSING INCLUDING AN ATOMIZING AIR ENTRY PORTCOMMUNICATING WITH AN ATOMIZING AIR PASSAGE BY WHICH ATOMIZING AIR ISPASSED TO A GUN, A CONTROL AIR ENTRY PORT COMMUNICATING WITH A CONTROLAIR PASSAGE BY WHICH CONTROL AIR IS DELIVERED TO A GUN, AN AUXILIARYPASSAGE IN SAID HOUSING CONNECTING THE ATOMIZING AIR ENTRY PORT ANDCONTROL AIR PASSAGE, AND A COCK OPERABLE TO OBTURATE THE AUXILIARYPASSAGE FROM THE ATOMIZING AIR ENTRY PORT AND TO CONNECT SAID PORT TOTHE ATOMIZING AIR PASSAGE OR TO OPEN THE AUXILIARY PASSAGE TO THEATOMIZING